Adjectives must match in gender and number with the noun they modify; therefore, all adjectives have masculine and feminine form. Nevertheless, some adjectives are invariable, meaning that the masculine and feminine forms are the same. For instance:

> El edificio azul --- La casa azul

As for nouns referring to people, some of them have masculine and feminine forms, which, again, can be the same or not. So we have:

 - Variable: *El conductor* --- *La conductora*
 - Invariable: *El artista* --- *La artista*

But some other nouns only have one form, which can be used for men and for women. Take into account that, in Spanish, grammatical gender has a strong correlation with sex, but does not always match. Some nouns, referring to people, which have only one gender:

> Judit Polgar fue un genio precoz del ajedrez.
>
> Tom Cruise es una estrella de cine.

Polgar is a woman and Cruise, a man, but you can use a masculine noun for her and a feminine one for him.